Apparatus for continuous treatment and processing of solid and/or liquid materials

ABSTRACT

Apparatus for the continuous treatment and processing of solid and/or liquid materials and consisting essentially of a rotatable cylindrical processing chamber having, in its interior, a rotary element which rotates at various angular velocities either freely or under drive.

Umted States Patent 1 [111 3,912,233

Stoeckelmann Oct. 14, 1975 [54] APPARATUS FOR CONTINUOUS 1,498,379 6/1924 Jahn 259/3 TREATNIENT AND PROCESSING OF SOLID 1,713,568 5/1929 Swenson 259/3 1,980,130 11/1934 Fasting 259/3 AND/OR LIQUID MATERIALS 1,991,959 2/1935 Roser 259/3 [75] Inventor; Guenter Stoeckelmann, 1,993,528 3/1935 Roser 259/3 Frankenthal-Moersch, Germany [73] Assignee: sche i g f s i 2 Primary ExaminerHarvey C. Hornsby i g Sc u wlgs a en Assistant ExaminerDona1d B. Massenberg me), erma y Attorney, Agent, or Firm-Johnston, Keil, Thompson [22] Filed: July 10, 1973 & Shurtleff [21] Appl. No.: 378,007

[30] Foreign Application Priority Data [57] ABSTRACT July 10, 1972 Germany 2233815 Apparatus for the continuous treatment and process- [52] US. Cl 259/3; 259/2 ing of solid and/or liquid materials and consisting es- [51] Int. Cl. BOIF 15/00 sentia11y of a rotatable cylindrical processing chamber [58] Field of Search 259/2, 3, 4 having, in its interior, a rotary element which rotates at various angular velocities either freely or under [56] References Cited drive.

UNITED STATES PATENTS 452,896 5/1891 Cam 259/3 3 Claims, 2 Drawing Figures US. Patent Oct. 14, 1975 APPARATUS FOR CONTINUOUS TREATMENT AND PROCESSING OF SOLID AND/OR LIQUID MATERIALS This invention relates to apparatus for the continuous treatment and processing of solid or liquid materials-or mixtures thereof which comprises a-rotatable cylindrical processing chamber having feeding and discharging means positively connected thereto at each end thereof.

Continuous treatment of products which are tacky or molten in an initial or intermediate stage of achemical or physical process before changing to a final solid state is very difficult on account of incrustation of the product on the walls of the apparatus due to the change of phase. Such incrustation must be constantly removed and this has previously been achieved by the use of scrapers only to an inadequate extent or with the absorption of'undue mechanical energy, since the forces occurring in dry friction are many times greater than in the case of liquid friction. In an apparatus which is operated continuously, steady state regions form in which both types of friction occur together, and this means that the rotor and the drive must be made to cope with very large forces, which however, occuronly rarely. Experience has shown that most apparatuses still become blocked. For example, medium to fast stirring elements in apparatus in which a major portion of the peripheral surface contacted by the product is scraped have not proved satisfactory for such cases. In the case of continuously operating'worms, which permit high energy densities at small effective volumes and low speeds, the conversion of the molten product to a solid product can be carried out only under specific conditions, i.e. when the frictional properties of the solid are reasonably favorable. However, the general use of worms for such purposes is opposed by the high investment and repair costs of such apparatus and their limited field ofapplication due to corrosion problems, since the worm spindles must be made of hardenable steels to reduce wear.

It has been found that, particularly where noncoherent and randomly distributed discrete bodies such as spheres or rods are used and are set inmotion by energy imparted thereto by the wall of the apparatus, such an apparatus, when operated continuously, will choke up slowly in the region of the melting zone, e.g. in the case of cylindrical drums such choking begins in the fillet region between the end wall and cylindrical wall. Since the grinding elements are unable to break up the fillet which forms in said region and which is maintained in a plastic state by the constant flow of product which melts on its surface, the fillet grows to a bead" which forces the grinding elements away from the melting zone and also throttles the freedom of movement of the grinding elements themselves. This process continues until the said bead seals up the feed means and the feed of product comes to a standstill. This choking phenomenon is the reason why a large number of melting or baking processes can only be carried out batchwise in heated ball mills or similar apparatus.

It is an object of the invention to provide an apparatus which fulfils the technological criteria in the continuous treatment and processing of solid and/or liquid materials and which ensures a uniform mechanical treatment of the products used. It is a further object of the invention to provide an apparatus which is simple and trouble-free and which also obviates choking of the feed means in continuous operation.

The present invention relates to apparatus for the continuous treatment and processing of solid and/or liquid materials, characterized by a symmetrical or asymmetrical rotary element provided within the processing chamber for rotation in the region of the end flange of the feed means, the speed of rotation of said rotary element being different from that of the processing chamber. In a particularly advantageous embodiment, the rotary element is in the form of a scraper and is eccentrically mounted, with respect to the treatment chamber, for free rotation therein.

By apparatus we mean rotary kilns, drum-type furnaces, mixers, rotary mills, drum mills, ball mills and similar apparatus. The processing chamber of said apparatus may contain, depending on the materials to be treated, grinding elements such as spheres, cylinders or rods, which grind and mix the contents of the chamber.

Process materials for the purposes of this invention are, for example, melts, solutions, pastes and powders which become converted to the solid state on passing through the apparatus. By treatment and processing we mean, in particular, such operations as mixing, homogenizing, grinding, stirring, dispersing, dissolving, heating, cooling and drying. Furthermore, reactions such as those between melts and gases or between melts and liquids can be carried out.

Suitable freely rotatable symmetrical or asymmetrical rotary elements are cruciform, stellate, disc-shaped, serrated and annular scrapers, generally provided with sharp edges at their periphery. I

The arms of cruciform or stellate rotary elements may have a variety of cross-sections. Deeply undercut triangular sections of adequate flexural strength are ad vantageous. lf provided with special tips, the scraper may also serve to scrape a portion of the cylindrical surface of a mixing autoclave so as to increase the desired effect of reducing incrustations in the particularly critical corner region. I

Depending on the design and on the type of drive use, etc., the scraper achieves, in its region of operation, a good to very good mixing effect which may assist the process and improve the quality of the product, since better mixing of the components leads to quicker conversion and better heat transfer. Further improvement of the heat economy may be achieved by making the rotary element coolable or heatable.

Usually, one scraper at the inlet end of the apparatus is sufficient, although the use of further scrapers operating in a similar manner is possible. Furthermore, the apparatus may be subdivided into separate reaction zones by partitions of various designs.

It is particularly advantageous to arrange the rotary element eccentrically to the processing chamber and freely rotatable therein so that a slight difference in the rotary speeds of the rotary element and the chamber is achieved. The degree of eccentricity determines the value of said speed differential. The rotary element, which is usually in the form of a scraper, is entrained by the friction occurring between the scraper and the chamber wall with product adhering thereto and also between the scraper and the charge consisting of mixing or grinding elements and product. Thus it is substantially dependent on the coefficient of friction between the material of which the scraper is made and the product and consequently varies as the consistency of the product changes. For the more viscous or harder products, entrainment of the scraper is better and more uniform and the removal of incrustation is effected with greater care on account of the minimum speed differential. A speed differential of zero, which is useless for achieving a scraping effect and which may occur on account ofjamming of a grinding element between the chamber wall and an arm of the scraper, will not harm the scraper or the chamber drive, since the freedom of rotation ensures that the jamming forces do not exceed a certain limit and also the jammed state is not permanent, since the jammed grinding element moves of necessity into the ejection zone of the eccentric, where it can move free from the scraper. An absolute scraper speed of zero is only possible when entrainment is inadequate due to an insufficiently large volume of charge or when the melt is too thin, but this state is also without danger to the scraper or its bearings, since it does not subject the scraper to high mechanical stresses.

An embodiment of the apparatus of the invention is described below by way of example with reference to the accompanying FIGS. 1 and 2, in which it is illustrated diagrammatically and in which:

FIG. 1 shows a cross-section of a freely rotatable and eccentrically mounted rotary element, and

FIG. 2 is a perspective view of the stellate rotary element used as scraper.

Referring to FIG. 1, the apparatus consists of a cylindrical processing chamber 1 having an internal flange 2 at one end thereof. The hollow shaft 3 is mounted in the fixed part 18 by means of radial bearings and axial bearings 11 located in positions upstream of the flange 2. The free end of said hollow shaft, which is provided with a stellate rotary element 4 to serve as scraper, projects into the chamber 1. The rotary element 4 consists of welded steel plates 5, 6, 7 and 8 and is mounted eccentrically to the processing chamber 1. The bearings 10 and 11 are sealed by means of retaining rings 12 and also by means of sealing washers 13 provided on the side of the said retaining rings remote from said bearings 10 and 11. Clamping of the bearings in the axial direction is effected by a nut 14. Sealing washers 15 prevent the penetration of product into the annular gap between the stationary charging means (not shown) and the rotating hollow shaft 3.

The cylindrical processing chamber 1 is driven by a chain-wheel 16 whose motion is transferred thereto via the bearing box 17 and the said flange 2. The feed of product takes place through the hollow shaft 3. The arms 9 of the rotary element 4 are immersed in the charge contained in the processing chamber and consisting of grinding elements and product and are entrained thereby by friction. They thus keep down the formation of incrustations of product, particularly in the region between the cylindrical wall of the chamber 1 and the flange 2.

I claim:

1. An apparatus for the continuous treatment and processing of solid or liquid products which change physical state during treatment, said apparatus comprising:

a rotatable processing chamber, said chamber having a substantially right cylindrical shape with an arcuate side wall and two substantially flat end walls, the first of said end walls having means through which said product is charged into said chamber, the second of said end walls having means through which said product is discharged from said chamber; grinding elements within said processing chamber;

and a scraper element arranged for rotating movement about an axis parallel to and eccentric with the longitudinal axis of said processing chamber, said scraper element being mounted freely rotatable about said parallel axis near the first of said chamber end walls; whereby said scraper is entrained to rotate by friction occuring between said scraper and said chamber first end wall and the product adhering thereto, and friction between the surface of said scraper and-the product and the fillet region formed by said arcuate wall and the first of said end walls is kept free of product deposits through a differential in the speed of rotation of said scraper and said processing chamber.

2. An apparatus as set forth in claim 1 wherein said scraper element is in the form of a disc-shaped scraper.

3. An apparatus as set forth in claim 1 wherein said scraper element is in the form of a stellate scraper. 

1. An apparatus for the continuous treatment and processing of solid or liquid products which change physical state during treatment,, said apparatus comprising: a rotatable processing chamber, said chamber having a substantially right cylindrical shape with an arcuate side wall and two substantially flat end walls, the first of said end walls having means through which said product is charged into said chamber, the second of said end walls having means through which said product is discharged from said chamber; grinding elements within said processing chamber; and a scraper element arranged for rotating movement about an axis parallel to and eccentric with the longitudinal axis of said processing chamber, said scraper element being mounted freely rotatable about said parallel axis near the first of said chamber end walls; whereby said scraper is entrained to rotate by friction occuring between said scraper and said chamber first end wall and the product adhering thereto, and friction between the surface of said scraper and the product and the fillet region formed by said arcuate wall and the first of said end walls is kept free of product deposits through a differential in the speed of rotation of said scraper and said Processing chamber.
 2. An apparatus as set forth in claim 1 wherein said scraper element is in the form of a disc-shaped scraper.
 3. An apparatus as set forth in claim 1 wherein said scraper element is in the form of a stellate scraper. 